The purpose of this study is to undertake a comprehensive investigation of collaborative learning in teaching English as a Foreign Language (EFL) speaking: a case study in Indonesian higher education context, with a focus on the perspectives of both lecturers and students. A case study was conducted using a qualitative research method to gather the data. Data were collected through in-depth interviews, focus group discussion, field notes, observations, document analyses, and audio recordings. To analyze the data, an interactive data analysis technique was utilized consisting of four stages: gathering, reducing, displaying, and drawing conclusions. According to the results, lecturers’ perceptions were categorized into three categories: (1) highly perceived collaborative learning (HiperCoL), (2) moderately perceived collaborative learning (MoperCoL), and (3) low perception of collaborative learning (LoperCoL). This study revealed two main stages of collaborative learning implementation: (1) integrating the ELT curriculum, and (2) designing collaborative learning: planning, monitoring, assisting, consolidating, reflecting, and evaluating. The impact of CL in EFL classrooms affects students’ achievement and changing behavior, such as (1) improving social interaction skills, (2) strengthening students’ psychological ability to speak more confidently, (3) increasing academic achievement, and (4) developing language (speaking) productivity. This study identified (1) highly responsive collaborative learning (HirCoL), (2) moderately responsive collaborative learning (MorCoL), and (3) low response to collaborative learning (LorCoL). Nevertheless, this study did not explore lecturers’ or students' perceptions of the impact of CL on their progress in their listening skills. Therefore, future studies should use phenomenological, narrative inquiry, and ethnographic design. Additionally, students’ expectations and motivation to collaborate were not explored in this study. However, this limitation should be addressed in future studies.
Keywords: Case Study, Collaborative Learning, Implementation, Impact, Perception.